1938 Rudge Race Bike

greg brillus

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The speed wobble seems to be an ongoing issue for you........I would be exploring why that is, perhaps it is the wheel/tire combination that is upsetting the bike, it does look high at the front of the bike, although I would have thought that would make the steering more stable........... I have learnt that the best way to improve a Featherbed type framed bike, from some of their bad handling characteristics is to lower the front of the frame, that is jack the rear higher and lower the front. This makes the steering much sharper, and stops much of the common "Patter" that occurs on hard cornering on these bikes to the front wheel. One of our boys here that I have raced against runs a pre war 500 BSA....... I know when I have followed him at a descent pace into a certain left hander at one of our tracks, I have seen his bike start to wobble quite badly, enough to slow him and I was able to quickly overtake him on the inside. I do remember on this same BSA that he too is running a large diameter front wheel/tire, perhaps a 21" I cant help but feel this is part of the problem........ Do you have other members of your race club that can give some useful advice, ones that have had similar issues on similar bikes............ Good luck........ Cheers......... Greg.
 

Nulli Secundus

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Thanks Greg for your valued input on this. Yes the dreaded speed wobble is indeed an ongoing issue for me whilst racing this bike. I completely agree that the 21 inch front wheel does not look right and makes the front end high. I do not know why the previous owner and builder of this bike went for a 21" front, which to me looks like a bicycle tyre, when 1938 Rudge Specials and Sports Specials had 19" wheels all round.

The 1938 Ulster, which this is not, had a 21" front and 20" rear. So why did he almost copy that when a rear 20" precluded racing? Maybe the Ulster had fine steering?

I have a 19" front wheel with an alloy rim. This is illegal, but that does not seem to stop others fitting them in the Girder Fork class. The problem is it is a replica hub made of alloy, with shrunk in brake drum and I think metric bearings. My wheel spindle will not fit it and I do not have the means to make one.

I have been chatting with davidd and his advice is great. From this I am thinking that I am partly responsible for the wobbles. In my first race, I followed the advice of the previous owner and sat further back and lent over the tank. I also followed advice from BigEd and did what his brother Peter did when racing a Sunbeam, which was locking my knees on the tank and my elbows against my knees. The bike behaved admirably, but even though I was convinced I was faster, the lap times proved otherwise. I think in other races I must of failed to nail this riding technique. Perhaps because of on track distractions, or physical capabilities.

At the end of the day though it would be preferable if the bike handled better.

Whist I consider Gerrards as my nemesis corner, in previous years I have had worse wobbles at the Esses, when the bike seemed to be leaping sideways towards the kerb and bucked me off the saddle. My inside left leg kept me hooked on in a sort of Randy Mamola esque style. So the good news is, my changed riding position suited not only the Esses, but also it was better coming out of the Bus Stop chicane and heading for the start/finish straight, where it had wobbled before.

Please keep the advice, suggestions and theories coming.

Cheers

David
 
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Bill Thomas

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Hello Nulli, I don't like these modern tyres, Any chance of getting a Ribbed front tyre.
Have you checked to see what the Trail is ?.
What tyre pressure do you use, For such a light machine, I would only go 22 or 24 on the front.
I see you have an Hydraulic Steering Damper now, I would have thought that would help a lot.
Cheers Bill.
 

greg brillus

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It probably "Is" helping a lot, but using one won't necessarily stop a speed wobble....... I have a good friend here who runs a very quick pre war Es 2 Norton, I will ask his thoughts on this issue, as he has been racing for a very long time.........Cheers.......... Greg.
 

Nulli Secundus

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Hello Nulli, I don't like these modern tyres, Any chance of getting a Ribbed front tyre.
Have you checked to see what the Trail is ?.
What tyre pressure do you use, For such a light machine, I would only go 22 or 24 on the front.
I see you have an Hydraulic Steering Damper now, I would have thought that would help a lot.
Cheers Bill.
I probably could try a ribbed tyre, but I am not a fan and actually prefer the modern tyres. I ran a tad under 24psi at Mallory and 26 rear. I have not checked the trail.

I also upped the friction damper to assist the hydraulic one.

Cheers

Dave
 

Nulli Secundus

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It probably "Is" helping a lot, but using one won't necessarily stop a speed wobble....... I have a good friend here who runs a very quick pre war Es 2 Norton, I will ask his thoughts on this issue, as he has been racing for a very long time.........Cheers.......... Greg.

Thanks Greg, I hope he can throw some light.

Cheers

Dave
 

vibrac

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I have gone crosseyed on the venhill web site looking for that long reach decompressor a curse on all web sites that start "make year model" do you have a link or perhaps a seller at next week's Stafford?
 

BigEd

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Dear Dave,
It sounds as if you made some progress at Mallory. It helps to look for the positives while you sort out the negatives.
You need to be comfortable on your Rudge and find a riding style that works for you. There is never enough time at a race meeting to sort out everything on a bike so try to concentrate on one area at a time. It is tempting to use a shotgun approach and change lots of things at once. It is then difficult to know which change improved things or made them worse.
It is good to talk to other riders and listen to any advice that may help but bear in mind that very few of the riders at current Vintage meeting are riding or have experienced riding girder fork rigid rear end machines. Listen and maybe try suggestions but you decide what works for you.
There is seldom a magic wand that will suddenly turn a machine rider combination into a race winner.
When my brother started racing my Sunbeam it was the 1970's. We had a good grid of pre-'34 bikes, all girder forks and no rear suspension. It was easier to gauge where we were against the opposition. (Somewhere near the back at the beginning.:rolleyes:)
Priority number one was reliability. More speed is good but not if you keep breaking down. You then miss out on track time and get less racing for your entry fee. (Most depressing.)
We were tight budget racing, not very technical but we did have "The Book" where we kept a record of results at each meeting, track conditions, wet/dry, changes to jetting, gearing etc. Finishing positions were noted but more important was logging lap times. Lap times are the best gauge of progress.
I don't know what meetings you are hoping to do this season but I hope to get to a few more Vintage race meeting this year so I'll try to find you in the paddock if I'm not intruding.
Next meeting is Darley Moor, not too far for me but unfortunately, I am away that weekend on a motorcycling weekend with 20 or so friends. I'll also miss out on the Bill Hancock Rider's Rally too where the venue is the Triumph factory, quite literally 5 minutes from my home.
 

Nulli Secundus

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I have gone crosseyed on the venhill web site looking for that long reach decompressor a curse on all web sites that start "make year model" do you have a link or perhaps a seller at next week's Stafford?


Or possibly this might be better


Unfortunately you have to buy a lever you might not want.
 
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